Touch screens in the market comprises separate type and in-cell type. A touch panel and a liquid crystal panel of a separate type touch screen need to be produced separately, and then assembled together. However, the touch screen made through this method has the defects of high cost and large size, as well as poor visibility due to the physical space between the touch panel and the liquid crystal panel that will reflect incoming light. As to an in-cell touch screen, a touch sensor is embedded in a liquid crystal display panel thereof, thereby incorporating touch function into the liquid crystal display panel. As compared with the separate type touch screen, the in-cell touch screen obviously has smaller size and better performance.
Further, in-cell touch screens can be divided into two types, namely self-capacitive screen and mutual capacitive screen. A single layer self-capacitive screen is the main research interests of an in-cell touch panel manufacturer. In the single layer self-capacitive screen, electrode units are usually arranged on a glass surface as an array, i.e., an electrode array is arranged. The electrode units in the electrode array are electrically isolated from one another, and each are coupled with the earth to form a capacitor. The capacitors formed are self capacitors. When the self-capacitive screen is touched by a finger, capacitance from the finger will be added to the screen capacitance, thereby increasing the capacitance value of the screen. In this case, the position touched by the finger, i.e., the coordinates of the finger, can be determined through detecting the changes of capacitance. The specific determination method is as follows: when being touched, the electrode array on the self-capacitive screen is scanned and detected successively in horizontal and vertical directions, and the horizontal and vertical ordinates thereof are respectively determined according to the changes in capacitance value before and after the touch, and then combined into a plane coordinates of the touch point. In other words, the touch point on the touch screen is projected respectively onto directions of an X axis and a Y axis through such scanning manner, and then the coordinates in the directions of the X axis and the Y axis are calculated, and finally combined into the coordinates of the touch point.
As shown in FIGS. 1 and 2, in a display region of an existing self-capacitive screen, a sensing layer made from transparent conductive material ITO is disposed under a pixel unit. The sensing layer is divided into a plurality of electrode regions each having the same area (about 5 mm×5 mm), which form the abovementioned electrode array. The electrode regions are electrically isolated from one another, and respectively correspond to six pixel units in the display region. The circuit connection schematically shown in FIG. 1 indicates that electrode regions 110 each need to be electrically connected with a control chip 130 through a separate wire 120, so that inductive signal (potential of voltage) of each electrode region 110 can be detected through the control chip 130. However, in the process of actual design and manufacturing, the electrode regions each are in bridge joint with the control chip through a via hole due to the limitation of manufacturing technology. In other words, a sub pixel of each pixel unit is provided with a via hole 140, so that the electrode region 110 under the pixel unit contacts the metal wire 120 above the pixel unit, which serves as an overline that is connected to the control chip 130, whereby the electrode region 110 can be electrically connected with the control chip 130. Specifically, as shown in FIG. 2, the metal wire 120 is disposed above a data line connected with each of the sub pixels, so as to avoid blocking the pixel electrode. In this case, although the problem of the detection and transmission of inductive signal is solved, part of the area of the pixel electrode is occupied due to the via hole, whereby an aperture ratio of the pixel electrode is reduced.